Speedometer not working 2003 F150 XLT
So I'm trying to fix my Dad's truck for him since he's somewhat mechanically not inclined.
Here's the problem:
The speedometer is intermittent but now mostly doesn't work. It pretty much stays at 150km/h. Strangely though it does kind of work in reverse. IE when speeding up the speedometer will slow down from 160 to 140.
Both cruise control and the odometer work totally fine.
There are two sensors on this truck, one on the tranny and one on the rear diff. My dad tried removing one sensor and put in a replacement but that didn't help.
I think it may be the gauge electronics since everything else is working well. The techs at the dealership are clueless about this - they didn't even know there were two sensors.
Anybody have any ideas??